Isolation and identification of postharvest pathogenic bacteria of Syzygium samarangense and antibacterial test of essential oils

Abstract

With Syzygium samarangense as the test subject，postharvest pathogenic bacteria were isolated，purified，and identified. Their pathogenicity was determined using Koch's postulates，and the antibacterial activity of 36 types of plant essential oils against highly pathogenic bacteria was assessed. The findings indicated that a highly pathogenic fungus was isolated and identified from naturally existing S. samarangense, labeled LW3-1. The pathogenicity rate of strain LW3-1 reached 100% within 2 days of inoculation, and molecular biology identified it as Colletotrichum gloeosporioides. Among the 36 essential oils, clove, geranium, myrrh, rose and sophora flavescens essential oils (1000 μl/L) had the most significant antibacterial effect on the LW3-1 strain, with an antibacterial rate of 100%. The antibacterial rate of 500 μl/L clove essential oil against the LW3-1 strain was still >85% after 12 days of treatment. In summary, it is determined that the pathogenic bacteria causing postharvest diseases of l S. samarangense is C. gloeosporioides, which is highly pathogenic. 500 μl/L clove essential oil has the best inhibitory effect on C. gloeosporioides.